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/*
Copyright (C) 2011 Sebastian Pancratz
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include <gmp.h>
#include "ulong_extras.h"
#include "fmpz.h"
void fmpz_gcdinv(fmpz_t d, fmpz_t a, const fmpz_t f, const fmpz_t g)
{
FLINT_ASSERT(fmpz_cmp(f, g) < 0);
if (fmpz_is_zero(f))
{
fmpz_set(d, g);
fmpz_set_ui(a, 0);
return;
}
if (!COEFF_IS_MPZ(*g)) /* g is small, hence f is small */
{
fmpz ff, gg;
ff = *f;
gg = *g;
_fmpz_demote(d);
_fmpz_demote(a);
*d = n_gcdinv((ulong *) a, ff, gg);
}
else /* g is large */
{
mpz_ptr atemp = _fmpz_new_mpz(), dtemp = _fmpz_new_mpz();
_fmpz_promote_val(d);
_fmpz_promote_val(a);
if (!COEFF_IS_MPZ(*f)) /* f is small */
{
mpz_t fptr;
fptr->_mp_alloc = 1;
fptr->_mp_size = 1;
fptr->_mp_d = (ulong *) f;
mpz_gcdext(dtemp, atemp, NULL,
fptr, COEFF_TO_PTR(*g));
}
else /* f is large */
{
mpz_gcdext(dtemp, atemp, NULL,
COEFF_TO_PTR(*f), COEFF_TO_PTR(*g));
}
if (mpz_cmp_ui(atemp, 0) < 0)
mpz_add(atemp, atemp, COEFF_TO_PTR(*g));
_fmpz_clear_mpz(*d);
_fmpz_clear_mpz(*a);
*d = PTR_TO_COEFF(dtemp);
*a = PTR_TO_COEFF(atemp);
_fmpz_demote_val(d);
_fmpz_demote_val(a);
}
}